1. Field of the Invention
The present invention pertains to safety penetrating instruments and, more particularly, to safety penetrating instruments having portal sleeves for introduction into anatomical cavities and penetrating members with sharp tips for penetrating cavity walls and being automatically retractable upon penetration to protect tissue and organ structures within the cavities from the sharp tips of the penetrating members.
2. Discussion of the Prior Art
Penetrating instruments are widely used in medical procedures to gain access to anatomical cavities of various sizes; and, in particular, use of penetrating instruments has become an extremely popular and important first step in endoscopic, or least invasive, procedures to establish an endoscopic portal for many various procedures, most notably laparoscopy procedures, with access being established via a portal sleeve positioned during penetration into the cavity with the penetrating instrument. Such penetrating instruments include a penetrating member having a sharp tip or point to pierce or penetrate the tissue forming the cavity wall, and the force required to penetrate the cavity wall is dependent upon the type and thickness of the tissue of the wall. Once the wall is penetrated, it is desirable to protect the sharp tip of the penetrating member to prevent inadvertent contact with or injury to tissue or organ structures in or forming the cavity, and a particular problem exists where substantial force is required to penetrate the cavity wall or the cavity is very small in that, once penetration is achieved, the lack of tissue resistance can result in the sharp tip traveling too far into the cavity and injuring adjacent tissue or organ structures.
Safety trocars having a spring-biased protective shield disposed between an outer sleeve and an inner trocar are marketed by Ethicon, Inc. as the Endopath and by United States Surgical Corp. as the Surgiport. U.S. Pat. No. 4,535,773 to Yoon, No. U.S. Pat. No. 4,601,710 to Moll and U.S. Pat. No. 4,654,030 to Moll et al are illustrative of such safety trocars. A trocar disposed within a portal sleeve and retractable within the sleeve in response to an electrical signal generated when force from tissue contact is removed from the sharp tip of the trocar is set forth in U.S. Pat. No. 4,535,773 to Yoon.
While prior art safety penetrating instruments are widely used, they suffer from many disadvantages when used in the procedures for which they are presently recommended; and, additionally, prior art safety penetrating instruments cannot be used in many procedures for which safety of penetration is highly desirable along with introduction of a portal sleeve. One of the disadvantages of prior art safety penetrating instruments is that the safety shields protrude from the sharp tips of the penetrating members to protect the sharp tips upon penetration through tissue of the cavity wall such that use in penetrating small or narrow anatomical cavities is not feasible. Another disadvantage of prior art safety penetrating instruments is that the safety shields can produce an irregular surface or profile with the portal sleeves and the sharp tips of the penetrating members during penetration of tissue resulting in increased resistance from tissue during penetrating of a cavity wall, trauma and damage to tissue and possible jamming and trapping of tissue.